A solenoid described in German Patent 295 14 315 U1 includes a largely cylindrical hollow bobbin made of an insulating material that is provided with two relay connectors anchored in an end area of the bobbin and projecting axially therefrom, with which it is possible to wind the bobbin mechanically. The bottom of the bobbin forming the bottom of the winding space has variable adjacent winding levels in the axial direction which are offset against one another in the radial direction, with the transitions between the winding levels being designed as a bevel having an inclination of approximately 30 degrees. Except in the transition areas, the bottom of the bobbin is provided with grooves for the winding wire.
The disadvantage of the solenoid described in the above-mentioned German Patent 295 14 315 U1 lies, in particular, in the overall length of the solenoid, which is determined by the length of the relay connector. This makes the solenoid susceptible to damage, for example, when mechanically winding the coil wire. The relay connectors have a tendency to bend.
Another disadvantage is that different flat connectors for the electrical lines may require different manufacturing methods, which complicates the production process and makes it expensive.